Speaking as a user only, and someone who sometimes builds software that needs Qt4 or Qt5, Qt is definitely better than Gtk3. It has an odd 30MB base memory over

Speaking as a user only, and someone who sometimes builds software that needs Qt4 or Qt5, Qt is definitely better than Gtk3. It has an odd 30MB base memory overhead for any Qt window, but it just works, it doesn't require you to fix your theme on each Gtk3 release, and it doesn't have many regressions, like black rectangles visible for each window upon creation, before widgets are visible. It also didn't break its file selector from the previous release (Gtk2). Moreover, and this may be debatable, it didn't force ClientSideDecorations in the form of vertical space waste, at a time when vertical space is getting scarce and it's all just wider and wider, on everything, regardless of GNOME or Wayland use. Gtk3 had one job: make it work with Wayland and HiDPI, but like many open source projects they redid too much and broke more than they fixed. Case in point: just updated to Firefox 46 and it now requires Gtk3, which introduced many UI regressions and oddities. So, Qt is the better choice when compared to Gtk3, though those who don't feel the pain of Gtk3 and use GNOME may disagree. I use Qt apps on X, Wayland and Windows, for what it's worth.